1. Technical Field
The present invention relates generally to combustion gas turbine engines and, more particularly, to an improved seal for resisting leakage between and past combustor transitions in the combustor section of a combustion gas turbine gas engine. Specifically, the invention relates to a sealing device that includes a frame having a seal member mounted thereon, the seal member being manufactured out of a plurality of metal fibers.
2. Description of the Related Art
A combustion gas turbine engine is a device that includes a compressor section, a combustor section, and a turbine section. Large quantities of air are serially compressed in the compressor section, heated in the combustor section to such a state that its stored energy (relative to the surrounding conditions) is more than that required by the compressor section, and expanded through the turbine section. The turbine section develops sufficient power to at least drive the compressor section and preferably is capable of driving accessory equipment such as electrical generators and other such devices.
During the heating process, fuel is added to the air and the mixture is burned in the combustor section. In its simplest form, the rotating compressor and turbine components are directly connected on a common shaft, and excess power to drive the accessory equipment is directly extracted from the compressor-turbine shaft. The excess power output may additionally be extracted in the form of thrust or in the form of pneumatic power, depending upon the particular design of the engine and the specific application thereof.
In the operation of such engines, it is particularly preferred to maximize the efficiency of operation and to reduce the emissions resulting therefrom. Inasmuch as such engines typically operate at elevated temperatures and pressures, the leakage of air along unintended or undesirable flow paths can negatively impact the efficiency and/or emissions produced by the engine. It is thus preferred, as a general matter, to reduce undesired leakage within combustion gas turbine engines.
As is known in the relevant art, and as is shown generally in FIG. 9, the combustor section of the gas turbine engine typically includes a plurality of combustor baskets that are mounted circumferentially about an annular opening at the upstream end of the turbine section. The air is directed from the compressor section into a pressurized plenum within which the combustor baskets are disposed. The air travels into the combustor baskets where it is mixed with fuel and ignited. The combustion gases flow through the combustor baskets and into the turbine section, thus driving the turbine section and providing power to the compressor section and to the accessory devices.
During operation, it is preferred that the air in the pressurized plenum flow through the combustor baskets instead of leaking directly from the plenum into the turbine section. Combustor baskets accordingly are designed with appropriately shaped combustor transitions that are mounted circumferentially along the annular opening at the upstream end of the turbine section. Each combustor transition is of a shape to xe2x80x9ctransitionxe2x80x9d the combustor basket from a circular cross section to an annular sector of the annular opening to the turbine section.
To minimize air leakage between adjacent combustor transitions, it is known to provide one or more ridges on the side faces of adjacent combustor transitions, the ridges being offset from one another to provide a labyrinth seal between adjacent combustor transitions. Each labyrinth seal provides a tortuous path along which any leaking air must travel, with the tortuous path resisting the flow of air therethrough an thus resisting leakage.
While such labyrinth seals between adjacent combustor transitions have been at least partially effective for their intended purpose, such labyrinth seals have not, however, been without limitation. As is known in the relevant art, combustor transitions thermally grow from the time the combustion gas turbine engine is initially started until the time that steady state operation is achieved. A certain level of leakage remains during steady state operation.
The labyrinth seal between adjacent combustor transitions typically includes a pair of ridges on each of the confronting faces of adjacent combustor transitions to provide a pair of peaks and a valley therebetween. The peaks and valley of one confronting face are offset from the peaks and valley of the other confronting face such that when the combustor transitions thermally grow the peaks and valleys of the confronting faces mesh with one another to reduce the gap therebetween and to resist the leakage of air therepast.
While the configuration of such labyrinth seals can be designed about a given steady state operating temperature, such conditions typically are not achieved during startup operation of the engine or at steady state operation of the engine at a temperature other than the design temperature. Leakage through the labyrinth seals is difficult to eliminate regardless of the steady state temperature due to the inter-meshing configuration of labyrinth seals which typically permits at least a nominal quantity of air to leak therepast.
It is thus desired to provide an improved sealing device that can be used in conjunction with existing labyrinth seals of adjacent combustor transitions and that can reduce and resist the leakage of air past the labyrinth seals. It is additionally preferred to manufacture such a device out of materials that can withstand the elevated temperatures and pressures typically found in a combustion gas turbine engine.
A sealing device employed in a labyrinth seal between adjacent combustor transitions of a combustion gas turbine engine includes a frame and a seal member. The frame includes a seat and a connection tab, the seal member being mounted in the seat, and the connection tab being attached to a ridge of the labyrinth seal. The seat is configured to be received in the valley between a pair of adjacent ridges of a first combustor transition, with a ridge of a second combustor transition being compressively received against the seal member during thermal expansion and growth of the combustor transitions and the turbine engine. The seal member is advantageously manufactured out of a plurality of metal fibers, with the metal fibers and the frame each being suited to the elevated temperatures and pressures typically found in the combustion gas turbine engine.
An aspect of the present invention is to provide a sealing device for resisting the flow of gas through a labyrinth seal between a pair of adjacent combustor transitions of a gas turbine engine, the labyrinth seal including a first ridge disposed on each combustor transition, the first ridges being offset and adjacent one another, the general nature of which can be stated as including a seal member having a plurality of metal fibers, an elongated frame having a longitudinal axis, the frame being formed with a seat extending longitudinally along the frame and including a first connection tab protruding from the seat, the first connection tab being structured to be mounted on one of the first ridges of one of the combustor transitions, and the seal member being disposed in the seat.
Another aspect of the present invention is to provide a gas turbine engine, the general nature of which can be stated as including a compressor section, a combustor section, and a turbine section, the compressor, combustor, and turbine sections being in fluid communication with one another, the combustor section including a first combustor transition, a second combustor transition, a labyrinth seal between the first and second combustor transitions, and a sealing device as set forth in the previous paragraph. The labyrinth seal includes a first ridge mounted on the first combustor transition and extending in a direction generally toward the second combustor transition and a first ridge mounted on the second combustor transition extending in a direction generally toward the first combustor transition, the first ridges of the first and second combustor transitions being offset from one another.
Still another aspect of the present invention is to provide a method of resisting the flow of gas through a labyrinth seal between a pair of adjacent combustor transitions of a gas turbine engine, the labyrinth seal including a first ridge disposed on each combustor transition, the first ridges being offset and adjacent one another, the general nature of which can be stated as including the steps of positioning a seal member in a frame, the seal member including a plurality of metal fibers, the frame including a seat and a first connection tab extending outwardly from the seat, mounting the first connection tab to the first ridge of one of the combustor transitions, and compressing the first ridge of the other combustor transition into the seal member.